Machines for processing flat strips, sheet or web material, while moving through the machine usually involving cutting the material into suitable lengths or otherwise processing it are widely used. In any application it is important to measure the amount of length of travel of the material at suitable intervals. This is accomplished by utilizing a rotating wheel rotated by frictional contact with the surface of the moving material. The wheel is usually mounted above the material and is coupled to various counting devices such as pulse generators, tachometers, of transducers. The latter may in turn be connected to controls which govern the action of devices such as cut-off knives and other operations, which act on the moving material at selected intervals.
Illustrations of these are FIG. 14 of applicant's U.S. Pat. No. 4,183,271, FIG. 3 of Tokuno U.S. Pat. No. 4,020,406. Also illustrative are U.S. Pat. No. 3,716,773 to Raoul and U.S. Pat. No. 4,481,715 to Gilmore.
In all previous applications the measuring wheel is mounted on shafts or pivoted swing arms above the moving material and the force of gravity alone is relied upon for the periphery of the wheel to make continuous contact with the material, sometimes aided by springs, but with no precautions for accuracy under varying conditions of material travel as set forth below.
The problem of making an accurate measurement of the periodic lengths of material passing along the wheel is important for proper function of the operations performed by the machine on the material as controlled by the measuring wheel.
This becomes especially important where linear speeds of the material may vary from zero to 1,000 feet per minute. The motion or movement of the moving material may deviate laterally and sometimes suddenly by as much as 1" of the material or 10 degrees lateral swing of the arm holding the wheel. It may also bounce vertically as much as 11/2". Such action causes skidding of the wheel and interferes with proper contact between the wheel and the material. This affects the accuracy of the measurement.
In none of the prior art known to me is any provision made for taking care of these conditions to effect greater accuracy of the measurement and hence the subsequent operations.